itch.io

An idea would be to not attach the second end of the line to the mouse but instead attach the first one to the ball.
I would also try to hide the cursor when doing that, so that the user doesn't get to see that the mouse is not where he's aiming at, and show the cursor again after the shooting is done.

Effectively you still have the line represent the relative mouse movement, but hide the mouse so it isn't visible that the mouse and the line's end are not at the same place because of the camera movement.

Well... that might or might not feel/look better, but you can try and see if you like it..

On a side note,
Could you not require that the player to actually click at the ball to start aiming a shot?
It's a bit hard to click on the ball when the camera has moved, and sometimes i feel like i do click on it but it just doesn't accept my clicks properly. Being able to start a shot by clicking anywhere would make the game easier to play.

That one might be a bit more about me having hard time completing the game and blaming it rather my skills, but would like to hear your opinion on it.
Keep in mind this is your game and you decide how to develop it.

Edit:
Huh, i can actually start anywhere when the ball is not moving.
And i can't figure out where i can and can't do so when the ball is moving.

Edit 2:
I think i figured that mechanic: You can't start a shot if the ball is moving too fast.
Now that i know i can actually start dragging anywhere, it does make sense why you did the line that helps with the aim that way.

Edit 3:
This has become a wall of text at this point... Sorry about that.
If the player is expected to play slowly (as you can't stop and redirect a fast ball), doesn't this make the game a bit speedrun unfriendly?